The present-day fire hydrant valves are composed of a flap removably engaged in a valve seat, wherein the flap is maintained in closed position with a valve stem extending from the aboveground section of the fire hydrant conduit. In a usual configuration, the valve seat is threadable with the body section of the elbow of the fire hydrant conduit. To disengage the flap from the seat and to open the valve, an operator has to apply a thrust downwardly on the stem via an operating nut located in the head of the fire hydrant conduit. Thus, the stem must be made of a rigid material and must present a strong section since a significant pressure is applied on it when opening the valve.
Additionally, the present-day fire hydrant valves are composed of an important number of parts rendering the maintenance operations costly and time-consuming. Moreover, such a great number of parts make the present-day fire hydrant valves vulnerable to frost damage in cold climate regions. Additionally, the operating nut and other parts extending aboveground are more subject to frost than the buried parts of the valve. Thus, the operation and the maintenance of the fire hydrant valves, and also of the fire hydrant conduits, can be grueling for some regions, especially during cold weather, for all these reasons.
Water hammer phenomena can also be observed occasionally in present-day fire hydrant valves since a great amount of slack or allowance is induced in the fire hydrant conduits by the various combined components working under high stress.